What’s the historic success rate of Missions to Mars?

Sending a spacecraft to Mars is obviously extremely complex. For this reason, the first mission that Mars One will send to the surface of Mars, will be a full demonstration mission, using a controlled lander. Assuming this mission succeeds, more cargo missions will follow. Also see the Mars One roadmap.

Each of these relatively low-risk cargo missions will teach us more about the end-to-end process. Meticulous analysis of mission data from each mission will provide invaluable knowledge that can be used to ensure that future missions run as smoothly as possible, and that all possible safeguards and system redundancies have been properly implemented. In this way, all risks to payloads and transport vehicles can be absolutely minimized.

Only after all cargo has successfully landed, and the mission process has been perfected as far as is humanly possible, will our first crew depart, using an identical system.